全文获取类型
收费全文 | 1273篇 |
免费 | 78篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 336篇 |
金属工艺 | 30篇 |
机械仪表 | 30篇 |
建筑科学 | 23篇 |
能源动力 | 79篇 |
轻工业 | 185篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 128篇 |
一般工业技术 | 320篇 |
冶金工业 | 68篇 |
原子能技术 | 10篇 |
自动化技术 | 124篇 |
出版年
2023年 | 52篇 |
2022年 | 58篇 |
2021年 | 87篇 |
2020年 | 60篇 |
2019年 | 72篇 |
2018年 | 84篇 |
2017年 | 70篇 |
2016年 | 77篇 |
2015年 | 42篇 |
2014年 | 62篇 |
2013年 | 98篇 |
2012年 | 61篇 |
2011年 | 80篇 |
2010年 | 58篇 |
2009年 | 46篇 |
2008年 | 45篇 |
2007年 | 36篇 |
2006年 | 17篇 |
2005年 | 16篇 |
2004年 | 23篇 |
2003年 | 15篇 |
2002年 | 13篇 |
2001年 | 11篇 |
2000年 | 11篇 |
1999年 | 6篇 |
1998年 | 17篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有1359条查询结果,搜索用时 15 毫秒
1.
2.
Wireless Personal Communications - Recently, the theory of effective rate has attracted much attention, since it can take the delay aspect into account when performing channel capacity analysis. In... 相似文献
3.
Yaseen K.R. Shariff Harish K. Choudhary Vijay Khopkar Ankit Yadav R. Madhusudhana Balaram Sahoo 《Ceramics International》2021,47(10):14907-14912
We report the mechanism involved in sol-gel auto-combustion synthesis of Ba–Sr-hexaferrite (Ba1-xSrxFe12O19; x = 0, 0.25, 0.5, 0.75 and 1, BSFO) ceramic powders through the analysis of the phases evolved during annealing of the as-synthesized powders, along with their structure and morphological studies. The XRD patterns of the as-synthesized samples indicate the formation of barium/strontium monoferrite ((Ba/Sr)Fe2O4) and maghemite (γ-Fe2O3) phases along with a minute amount of hematite (α-Fe2O3) phase. Annealing of these samples facilitates formation of BSFO phase through the solid state reaction between BaFe2O4 and γ-Fe2O3 phase. Interestingly, after annealing the samples with x = 0, 0.5 and 1, at 1000 °C for 2 h, we observed that phase pure Ba–Sr hexaferrite structure forms, but for samples with x = 0.25 and 0.75, high amount of hematite (α-Fe2O3) phase is observed, especially for x = 0.75. The reason associated with this could be the large difference between the ionic radii of Ba2+ and Sr2+ ions occupying the oxygen site. Furthermore, our study on annealing dependent phase evolution confirms that, this difference in ionic radii forbids the formation of a single phase Ba–Sr hexaferrite. The growth of clear hexagonal-shaped plate-like particles with varied particle sizes was observed for all the samples. The particle size variation may be due to the influence of the ionic radii difference on the sinterability of the samples. Our study provides a better understanding of synthesis mechanism of Ba–Sr hexaferrite samples. 相似文献
4.
5.
6.
Multimedia Tools and Applications - In the way of communication, facial expression act as non-verbal communication and play an important role in social interaction by providing some contextual... 相似文献
7.
Alan Pasha Tabatabai Daniel S. Seara Joseph Tibbs Vikrant Yadav Ian Linsmeier Michael P. Murrell 《Advanced functional materials》2021,31(10):2006745
Unlike nearly all engineered materials which contain bonds that weaken under load, biological materials contain “catch” bonds which are reinforced under load. Consequently, materials, such as the cell cytoskeleton, can adapt their mechanical properties in response to their state of internal, non-equilibrium (active) stress. However, how large-scale material properties vary with the distance from equilibrium is unknown, as are the relative roles of active stress and binding kinetics in establishing this distance. Through course-grained molecular dynamics simulations, the effect of breaking of detailed balance by catch bonds on the accumulation and dissipation of energy within a model of the actomyosin cytoskeleton is explored. It is found that the extent to which detailed balance is broken uniquely determines a large-scale fluid-solid transition with characteristic time-reversal symmetries. The transition depends critically on the strength of the catch bond, suggesting that active stress is necessary but insufficient to mount an adaptive mechanical response. 相似文献
8.
Wireless Personal Communications - The paper reports the performance of an energy harvesting cognitive radio network under primary user emulation (PUE) attack. A secondary user (SU) can harvest... 相似文献
9.
Chandra Sekhar Yadav G. V. P. Ghali V. S. Baloji N. R. 《Russian Journal of Nondestructive Testing》2021,57(6):486-499
Russian Journal of Nondestructive Testing - Characterization of various industrial components without impairing their future utility increases the necessity of nondestructive testing (NDT)... 相似文献
10.
Dr. Krishan Kumar Lalit Yadav Prof. Paturu Kondaiah Dr. Sandeep Chaudhary 《ChemMedChem》2019,14(18):1633-1640
In this study, we developed redox-sensitive vesicles using synthesised lipoyl cholesterol derivatives, a non-ionic surfactant and an optimum level of free cholesterol. Interestingly, concentration-dependent self-assembly was observed by scanning electron microscopy, wherein vesicles manifested as hollow spherical (at 0.15 mm ) and triangular (0.50 mm ). The redoxresponsive characteristics of the vesicles was probed in the presence of dithiothreitol; they underwent a clear increase in size as observed by dynamic light scattering measurements. These vesicles could easily encapsulate an anticancer drug, doxorubicin, and were observed to be stable in the presence of serum. They showed substantial release of the drug in response to biologically relevant stimulus, that is, glutathione. A toxicity assessment on HeLa and HepG2 cancer cells demonstrated activities of the drug-loaded vesicles comparable to that of free drug, whereas significantly enhanced toxicity and apoptotic induction were observed against drug-resistant HeLa cells, which was determined by studying the cellular internalisation of doxorubicin. 相似文献